Why it effects some systems is a mystery that can't be solved without a look at multiple effected systems. If your system is working leave it alone. You can always go to your backup when there is a problem. You would just be making my mistake in reverse.

Well I just finished re-installing DVDSP and now it just sits on the splash screen for a while then quits. Officially buggered. I saw this on a macbook the other day - just sitting on the splash screen forever with nothing else happening, but thought it was machine specific. Obviously not.

FCP has failed now, which sucks. Crashes on opening just like DVDSP. It's possible it's another issue, I'll report back with logs for anyone interested when I have a minute. Meantime, my assumption is that the prokit upgrade i not really fun. Don't go there.

Too late. I went there and failed miserably. I couldn't open fcp, compressor, dvdsp etc. I just spent two days tinkering around and re-installing the os and fcp studio 3. Unfortunately I didn't see this thread until now. I thought it was something I was doing wrong and I was going insane because of it. Now I can sleep a little easier.

OK got a minute and ran Jon Chappell's FCS Maintenance Pack and the problem is definitely ProKit. I've backtracked ProKit, run cleanups, re-installed DVDSP and still nada. Lucky for me I have another internal drive that runs a clean stable system, but if you're not backed up stay away from this update! Wonder if we should make this a sticky until there is a repair..